# Growth rate control in unstructured blocks

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 November 3, 2013, 09:25 Growth rate control in unstructured blocks #1 Senior Member   Ali Join Date: Jan 2012 Location: Pakistan Posts: 135 Rep Power: 9 Sponsored Links Hi, How can the growth rate be controlled in unstructured blocks? Near the wall cells are small and immediately cell size becomes larger. I need a smooth transition but keeping the mesh size low. __________________ Best Regards Ali

November 3, 2013, 21:12
#2
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Chris Sideroff
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Quote:
 Originally Posted by Hybrid Hi, How can the growth rate be controlled in unstructured blocks? Near the wall cells are small and immediately cell size becomes larger. I need a smooth transition but keeping the mesh size low.
Increase the boundary decay in the solver attributes. I typically use somewhere in the range of 0.85 - 0.95.

If you want more explicit size control you can cap the element sizes with min and max edge lengths in the same panel as above.

If that's still not getting you what you want, create a nested block and use the domains at the block interface to better control the rate at which the elements grow.

-Chris

 November 4, 2013, 13:19 Geometry Import problem #3 Senior Member   Ali Join Date: Jan 2012 Location: Pakistan Posts: 135 Rep Power: 9 I have problem with geometry import in Pointwise v17.1 R2. I made the model in SpaceClaim, when I tried to import in Pointwise, the rounded surfaces missed, making sharp edges. How can I solve this problem? __________________ Best Regards Ali

November 4, 2013, 16:04
#4
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Chris Sideroff
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Quote:
 Originally Posted by Hybrid I have problem with geometry import in Pointwise v17.1 R2. I made the model in SpaceClaim, when I tried to import in Pointwise, the rounded surfaces missed, making sharp edges. How can I solve this problem?
OK this is a different problem so you should have opened a new thread. Anyway do so next time. I will answer you question here.

Two main questions:

1) What format did you export from SpaceClaim?
2) What is the approximate bounding box size of the geometry? That is if you drew a box that contained all of the geometry, what would the length of the boxes diagonal be (roughly)?

-Chris

November 5, 2013, 05:39
#5
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Ali
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Quote:
 Originally Posted by cnsidero OK this is a different problem so you should have opened a new thread. Anyway do so next time. I will answer you question here. Two main questions: 1) What format did you export from SpaceClaim? 2) What is the approximate bounding box size of the geometry? That is if you drew a box that contained all of the geometry, what would the length of the boxes diagonal be (roughly)? -Chris
1)- I tried a number of formats like STEP, IGES, Parasolid.
2)- L = 2000mm and H=W=150mm, diagonal = 2005mm
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Ali

November 5, 2013, 09:40
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Chris Sideroff
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Quote:
 Originally Posted by Hybrid 1)- I tried a number of formats like STEP, IGES, Parasolid. 2)- L = 2000mm and H=W=150mm, diagonal = 2005mm
When you import, the IGES for example, what does the Total Grid/DB Length report at the top of the File > Properties panel in Pointwise?

November 6, 2013, 03:28
#7
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Ali
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Quote:
 Originally Posted by cnsidero When you import, the IGES for example, what does the Total Grid/DB Length report at the top of the File > Properties panel in Pointwise?
The Total Grid/DB Length is almost twice the L=2000 (Enabaled and Visible Grid/DB Length).

What is the significance of Total Grid/DB Length?
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November 6, 2013, 08:25
#8
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Chris Sideroff
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Quote:
 Originally Posted by Hybrid The Total Grid/DB Length is almost twice the L=2000 (Enabaled and Visible Grid/DB Length). What is the significance of Total Grid/DB Length?
That value should be close to (within a factor of 10 is a good guideline) the Model Size parameter in the same panel. It's default is 1000 so you should be fine. Like any numerical software, the geometry kernel in Pointwise has a fixed floating point range so the Model Size is used to adjust it's internal tolerances to ensure optimal accuracy.

Are there any controls in SpaceClaim for tolerances, etc for export? I've have never used SpaceClaim before so you'll have to help me here.

We're getting to the point where a picture or the geometry would help. Can you post either or both?

 November 6, 2013, 12:22 #9 Senior Member   David Garlisch Join Date: Jan 2013 Location: Pointwise HQ Posts: 160 Rep Power: 6 If you could attach a CAD file that exhibits the problem, I can examine it more closely. If you are able, please also submit the file to PW support so we can track the resolution of this issue.

November 6, 2013, 13:22
#10
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Ali
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Quote:
 Originally Posted by cnsidero We're getting to the point where a picture or the geometry would help. Can you post either or both?
I will let you know about the SpaceClaim tolerance in detail tomorrow. As for as the geometry is concerned, it is not feasible/possible to post here but I can post a picture of it.

I will try to post the CAD privately if you feel comfortable with that.
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Ali

November 6, 2013, 21:44
#11
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Chris Sideroff
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Quote:
 Originally Posted by Hybrid I will let you know about the SpaceClaim tolerance in detail tomorrow. As for as the geometry is concerned, it is not feasible/possible to post here but I can post a picture of it.
That will help.

Quote:
 I will try to post the CAD privately if you feel comfortable with that.
If you're comfortable with that send me a PM.

 November 7, 2013, 07:17 #12 Senior Member   Ali Join Date: Jan 2012 Location: Pakistan Posts: 135 Rep Power: 9 Here is the pictures of geometry: https://www.dropbox.com/s/8y956mi1p9himar/geom.pdf __________________ Best Regards Ali

November 7, 2013, 14:18
#13
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Chris Sideroff
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Quote:
 Originally Posted by Hybrid Here is the pictures of geometry: https://www.dropbox.com/s/8y956mi1p9himar/geom.pdf
That helps a ton. Two things. First, it's possible the "defect" you're seeing in the small rounded surface is purely visual and not actual. To test this hypothesis, select those surfaces (or quilts), View>Attributes, check Advanced panel. Increase the triangle density to at least 100 or even 200 and click Apply. If you see the roundedness appear now it was just visual.

The triangle density controls how many triangles are used to render the surface. Even though the surface is mathematically defined (NURBS), to display the surface on the screen using OpenGL there has to be triangular representation of it.

Second, in the SpaceClaim IGES export options choose Manifold B-Rep Solid. Pointwise will recognize this entity type - the solid model - and you will likely save a lot of time by avoiding reassembly of the solid by saving it in the IGES file.

November 8, 2013, 09:00
#14
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Ali
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Quote:
 Originally Posted by cnsidero That helps a ton. Two things. First, it's possible the "defect" you're seeing in the small rounded surface is purely visual and not actual. To test this hypothesis, select those surfaces (or quilts), View>Attributes, check Advanced panel. Increase the triangle density to at least 100 or even 200 and click Apply. If you see the roundedness appear now it was just visual. The triangle density controls how many triangles are used to render the surface. Even though the surface is mathematically defined (NURBS), to display the surface on the screen using OpenGL there has to be triangular representation of it.
The rounded surface is not a visual effect, I tried your suggestion by increasing triangle density is useless.

Quote:
 Originally Posted by cnsidero Second, in the SpaceClaim IGES export options choose Manifold B-Rep Solid. Pointwise will recognize this entity type - the solid model - and you will likely save a lot of time by avoiding reassembly of the solid by saving it in the IGES file.
It works fine with IGES.
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November 8, 2013, 12:42
#15
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Chris Sideroff
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Quote:
 Originally Posted by Hybrid It works fine with IGES.
Does that mean the rounded surfaces are appearing as they should? Just want to make sure your issue is resolved.

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